Currently, commonly used disposable intravenous needles need to be sleeved with a needle sheath before use, so as to protect the needle head from being bent or bumped. During use, when the needle sheath is removed, a risk of puncture wound is easily caused. But the real danger is at the disposing stage after a transfusion is completed, when the needle has been pulled out from inside a body of a patient that has received transfusion, for discard disposal of the needle, the needle is put into a special disposal box or covered with a needle sheath, and as a result, a risk of puncture wound is easily caused, which might leads to serious consequences such as infection suffered by the medical staff.
In order to deal with such defect, some intravenous needle utilizes a technical means of retractable needle, wherein, after a transfusion is completed, by using an elastic force of a structure such as a spring, the needle head retracts into a protection sheath for protecting the needle head. As such, although the needle head is effectively protected and the medical staff is prevented from being wounded by puncture, however, a great deal of pain is suffered by the patient because of the mechanical motion of the retraction of the needle head.
On the other hand, when the retractable needle retracts, because the retractable mechanical structure thereof usually has gaps which might nip the skin of the patient, more pain might be suffered by the patient.